The present invention relates to a semiconductor device and a manufacturing method of the semiconductor device and in particular to a technique effectively applicable to a semiconductor device including a power supply circuit.
In recent years, the frequencies of power MOS-FETs (Metal Oxide Semiconductor Field Effect Transistors) used in power supply circuits have been more and more increased to accomplish the miniaturization and high-speed response of power supply circuits and the like.
With respect to CPUs and DSPs of desktop and notebook personal computers, servers, game machines, and the like, especially, there is a trend toward increase in current and frequency. To cope with this, technological development has been promoted with respect to power MOS-FETs, which construct non-isolated DC-DC converters for controlling power supplies to CPUs (Central Processing Units) and DSPs (Digital Signal Processors), so that they can accommodate large currents and high frequencies.
A typical DC-DC converter in widespread use as an example of power supply circuits is so constructed that a power MOS-FET for high-side switch and a power MOS-FET for low-side switch are connected in series. The power MOS-FET for high-side switch has a switch function for controlling the DC-DC converter and the power MOS-FET for low-side switch has a switch function for synchronous rectification. These two power MOS-FETs are alternately turned on/off in synchronization, and thereby convert power supply voltage.
For example, Japanese Unexamined Patent Publication No. 2002-217416 discloses a technique in which a power MOS-FET for high-side switch and a power MOS-FET for low-side switch are housed in one and the same package, and the efficiency of voltage conversion between the power MOS-FET for high side and the power MOS-FET for low side is thereby enhanced.
Further, for example, Japanese Unexamined Patent Publication No. 2001-25239 discloses a technique for reducing noise that poses problems in a DC-DC converter constructed of a control circuit, a driver circuit, and a power MOS-FET packaged in one chip, by a resistor and a capacitor.